That might be true. I remember finding several of them while looking for bugs. But I did find some of them on sunny days also.

Anyway, I completed the photo in one of my families, one other has 11 pieces. The last one I got was days after I opened the shed. And I'm almost sure that they show up more than once if you fail to pick up, since I missed one of the common ones once and now I have all the common photo pieces.